The effect of temperature rise on microstructural properties of cement-based materials

Abstract

This work reports on the influence of stray current flow on temperature rise in hardening cement-based materials and consequently altered cement hydration. To simulate stray current, different levels of electrical current were applied to cement paste and mortar specimens immediately after casting. Isothermal calorimetry tests were carried out to quantify the heat release and the degree of cement hydration. The results confirmedan increase in the degree of cement hydration as a resultof temperature increase due to electrical current flow. A simulation approach wasemployed to predict the temperature rise in cement-based materials when higher levels of stray current are involved. By incorporating an "electrical enhancement" factor, the degree of hydration and microstructural development of cement-based systems were simulated using HYMOSTRUC3D. These results also confirmed the expected acceleration of cement hydration within temperature rise due to electrical current flow.Densification of the bulk cement matrix would be relevant, following the aforementioned enhanced cement hydration, i.e. a positive effect of low level current densities could be at hand. However, detrimental effects e.g. current and/or temperature associated microcracking, internal stress etc., can be expected upon higher current density levels. This paper only focuses on illustrating the approach with regard "electrical enhancement" factor implementation in HYMOSTRUC3D and the validation of this approach through collected experimental data.